Result: Arsenal 1 (Lacazette 50'), Brighton and Hove Albion 2 (Webster 36', Maupay 80').
A fine performance from Brighton saw them win at Arsenal for the first time in their history, moving from 15th to 13th in the table.
Alexandre Lacazette marked his 100th Gunners appearance by heading his side level after Adam Webster had given the visitors a first-half lead.
With the score 1-1, there was frustration for Ljungberg and Arsenal when David Luiz thought he had made it 2-1 with a volley but it was correctly ruled out following a VAR check for offside.
Neal Maupay headed Brighton's winner from Aaron Mooy's cross to leave Arsenal on their worst winless run since 1977 and 10 points off a Champions League spot.
Arsenal, who are 10th in the table, have now failed to win any of their last nine games in all competitions and fans who stayed for the final whistle booed their team off the pitch after a lukewarm performance.
Premier League Weekend Fixtures:
Saturday, December 7
- Everton vs. Chelsea.
- Bournemouth vs. Liverpool.
- Tottenham Hotspur vs. Burnley.
- Watford vs. Crystal Palace.
- Manchester City vs. Manchester United.
Sunday, December 8
- Aston Villa vs. Leicester City.
- Newcastle United vs. Southampton.
- Norwich City vs. Sheffield United.
- Brighton & Hove Albion vs. Wolverhampton Wanderers.
Monday, December 9
- West Ham United vs. Arsenal.